1. Field of the Invention.
This invention relates to an improved implementation of a microprocessor integrated circuit design. In part, the microprocessor integrated circuit design concerns circuit implementations that give improved microprocessor performance and functionality. In part, the invention also relates to improved integrated circuit structure configurations. In particular, the invention relates to an improved data path multiplexing arrangement and busing structure. It further relates to a special ground balancing scheme that improves integrated circuit performance. The invention also relates to an improved register file storage circuit. The invention further relates to improved timing circuits for a microprocessor integrated circuit and related applications. It further relates to improved read only memory (ROM) circuits.
2. Description of the Prior Art.
A wide variety of integrated circuit microprocessors are now known in the prior art. All of the major semiconductor manufacturers in the United States offer such integrated circuits implemented in complementary metal oxide (CMOS) form or in bipolar integrated circuit form, whether in integrated injection logic (I.sup.2 L) or combined I.sup.2 L and transistor-transistor logic (TTL) form. For example, the commercially available F9445 Microprocessor Integrated Circuit, available from the assignee of this application, is a high performance combined I.sup.2 L and TTL integrated circuit. A further description of that integrated circuit is contained in the following copending, commonly assigned applications: Application Ser. No. 167,614 now Pat. No. 4,396,980 by Hemraj K. Hingarh, entitled "COMBINED INTEGRATED INJECTION LOGIC AND TRANSISTOR-TRANSISTOR LOGIC MICROPROCESSOR INTEGRATED CIRCUIT DESIGN", filed July 11, 1980, and Application Ser. No. 167,607 by Michael G. Mladejovsky, entitled "CYCLE COUNTER FOR MICROPROCESSOR INTEGRATED CIRCUIT", filed July 11, 1980. While the art pertaining to the design of microprocessor integrated circuits is therefore a well developed one, a need still remains for further improvements in such design in order to achieve greater levels of functionality and performance in high performance microprocessors.